The present invention relates to self-floating flexible pipes (or tubes), such as the lines of pipes of rubber or of an analogous material, which when connected to a petroleum installation permits off-shore filling of transport ships with petroleum products. In use, such a line of pipes consisting of self-floating pipes is left permanently floating on the water in a manner such that the personnel of a ship can easily locate same, seize a free end from the bridge of the ship, and connect this end to a duct (or line) leading to petroleum tanks.
A self-floating flexible pipe of this type comprises a reinforcing sheathing (reinforcing armature or armoring layers) which is placed in a rubber wall at the pipe and a layer of cellular material which covers the entire exterior face of this rubber wall. This cellular material, in which the majority of the cells are closed, which means that they do not communicate with each other, assures the floating of the pipe on the water. However, this cellular material layer is fragile because of the fact that it is very sensitive to deformations and is not very resistant with a consequent very rapid deterioration of the pipe to a non-usable condition due to the abrasion of the cellular material. In particular, such abrasion results in use of such pipes because in order to connect the free end of the pipe line to the duct of petroleum tanks, this cellular material layer is manipulated and bent under extremely severe conditions with contact with metallic parts of the ship.
It is contemplated by the present invention to provide a self-floating pipe of the type discussed above which does not have the above discussed disadvantages and without, however, interfering with advantageous intrinsic properties of the pipe (or tube) itself, particularly as far as the pipes longitudinal flexibility is concerned.
The present invention contemplates providing a peripheral layer of metallic cables or analogous elements having a high mechanical resistance on the exterior face of the cellular material of the self-floating pipes. The present invention further contemplates placing such cables side by side and winding them according to a setting angle in the range of 56.degree. to 68.degree. with respect to the longitudinal axis of the pipe. These cables form part of a sheathing skin on the radial outward surface of the layer of cellular material which is resistant against abrasion and shocks and thereby protects the cellular material. These cables play no role whatever in the armature (or armoring) of the pipe portion conducting the fluids, which pipe portion is on the radial inner surface of the layer of cellular material. Due to the configuration and orientation of the cables, they do not impair the longitudinal flexibility of the pipe.
The cables used in the peripheral layer surrounding the cellular material in the present invention are preferably metallic cables which display an elastic elongation, or cables on which the permanent undulations are produced for accommodating elastic elongation and retraction.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention.